Inspection Procedure 5
Inspection Procedure 5: Keyless entry system does not work.CAUTION: Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
OPERATION
The lock/unlock signals from the transmitter are received by WCM, and then sent to ETACS-ECU from WCM. When ETACS-ECU receives signals from the key reminder switch and all the door switches, ETACS-ECU actuates the keyless entry system.
PROBABLE CAUSES
- Malfunction of the key reminder switch
- Malfunction of the door switches
- Malfunction of keyless entry transmitter
- Malfunction of the WCM
- Malfunction of ETACS-ECU
- Damaged wiring harness and connectors
- Option coding information
DIAGNOSTIC PROCEDURE
Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
STEP 1. Scan tool (M.U.T.-III) CAN bus diagnostics
Use scan tool MB991958 (M.U.T.-III), diagnose the CAN bus lines.
Q: Is the CAN bus normal?
YES : Go to Step 2.
NO : Repair the CAN bus line (Refer to Controller Area Network, CAN bus diagnostics chart).
STEP 2. Using scan tool MB991958, read the diagnostic trouble code.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958. Refer to "How to connect scan tool (M.U.T.-III)." How to Connect the Scan Tool (M.U.T.-III)
2. Turn the ignition switch to the "ON" position.
3. Check whether the ETACS-ECU related DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Diagnose the ETACS-ECU. Refer to Chassis Electrical.
NO : Go to Step 3.
STEP 3. Check the power supply system
With the ignition switch in the LOCK (OFF) position, check if the following function operates normally:
- Headlight
- Hazard warning light
Q: Is the check result normal?
YES : Go to Step 4.
NO : Refer to Chassis Electrical, Malfunction of ETACS-ECU power supply circuit.
STEP 4. Verify the central door locking system.
Q: Does the central door locking system work normally?
YES : Go to Step 5.
NO : Refer to Body, Trouble Symptom Chart. Central Door Locking System
STEP 5. Using scan tool MB991958, check data list.
Check the signals related to the keyless entry system operation.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958. Refer to "How to connect the Scan Tool (M.U.T.-III)." How to Connect the Scan Tool (M.U.T.-III)
2. Turn the ignition switch to the "ON" position.
3. Check the ETACS data list.
- Turn the ignition switch to the LOCK (OFF) position.
- Close the driver's door.
- Close the passenger's door.
- Close the RH-side rear door.
- Close the LH-side rear door.
- Close the liftgate.
- Remove the ignition key from the ignition key cylinder.
4. Turn the ignition switch to the "LOCK" (OFF) position.
OK: Normal condition is displayed.
Q: Is the check result normal?
YES (Normal conditions are displayed for all the items.) : Go to Step 6.
NO (Normal condition is not displayed for item No. 254.) : Refer to Chassis Electrical, Inspection Procedure 2: ETACS-ECU does not receive any signal from the ignition switch (IG1).
NO (Normal condition is not displayed for item No. 256.) : Refer to Chassis Electrical, Inspection Procedure 5: ETACS-ECU does not receive any signal from the front door switch (LH).
NO (Normal condition is not displayed for item No. 257.) : Refer to Chassis Electrical, Inspection Procedure 6: ETACS-ECU does not receive any signal from the front door switch (RH).
NO (Normal condition is not displayed for item No. 258.) : Refer to Chassis Electrical, Inspection Procedure 8: ETACS-ECU does not receive any signal from the rear door switch (RH).
NO (Normal condition is not displayed for item No. 259.) : Refer to Chassis Electrical, Inspection Procedure 7: ETACS-ECU does not receive any signal from the rear door switch (LH).
NO (Normal condition is not displayed for item No. 260.) : Refer to Chassis Electrical, Inspection Procedure 9: ETACS-ECU does not receive any signal from the liftgate switch.
NO (Normal condition is not displayed for item No. 264.) : Refer to Chassis Electrical, Inspection Procedure 3: ETACS-ECU does not receive any signal from the key reminder switch.
STEP 6. Using scan tool MB991958, check pulse check.
Check the signals related to the keyless entry system operation.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958. Refer to "How to connect the Scan Tool (M.U.T.-III)." How to Connect the Scan Tool (M.U.T.-III)
2. Confirm the ETACS pulse check.
- Remove the ignition key from the ignition key cylinder.
OK: The scan tool (M.U.T.-III) tone alarm sounds.
Q: Is the check result normal?
YES : Go to Step 7.
NO : Refer to Inspection Procedure 7.
STEP 7. Retest the system.
Check if the keyless entry system works normally.
Q: Is the check result normal?
YES : Intermittent malfunction (Refer to General (Body and Chassis) - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction).
NO : Replace WCM and register the ID codes.